This invention relates to an article method for modifying instruments of the type having a single series of markings of one measurement system to include another series of markings of another measurement system. For example, the article and method of the present invention is particularly useful for modifying automobile speedometers having only miles per hour markings to include kilometers per hour markings.
It has been proposed that all signs on United States federal highways which presently indicate speed limits in miles per hour be replaced with signs indicating speed limits only in kilometers per hour. This is part of an overall program to convert standards of measurement in the United States from the English system to the metric system. It has also been proposed that, in the interest of cost savings, a direct change from miles per hour to kilometers per hour be made without an interim change wherein signs would show speed limits in both miles per hour and kilometers per hour.
While certain late model automobiles manufactured in the United States have speedometers including an auxiliary scale showing kilometers per hour, a substantial number of automobiles in use in the United States today have speedometers having only miles per hour scales. The present invention provides an article and method for adding to such speedometers scales showing speeds in kilometers per hour. While the present invention specifically contemplates modification of automobile speedometers, its application is not limited thereto. Rather, the invention may be used in connection with the modification of any instrument to include markings corresponding to a system of measurement different from that of the pre-existing series of markings on the instrument.
It has previously been known to add additional series of markings to instruments by covering the entire face of the instrument with a sheet having the additional series of markings thereon. A drawback in this regard is the great variation often encountered in the sizes and shapes of instrument faces and the consequent need for stocking many different sizes and shapes of sheets. This problem is particularly severe in the case of automobile speedometers where the variations in instrument faces of different models of automobiles are pronounced.